The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Tour de France prompts bike safety warning

Fear of a Tour de France-led surge in the number of cyclists on NSW roads has sparked a new safety campaign to reduce deaths in the state.

The famed bicycle race begins in Corsica on Saturday.

It comes as nine cyclists have died on NSW roads this year - three times more than during the same period last year and already two more than the whole of 2012, according to the NSW Centre for Road Safety.

The campaign is being jointly launched by the Centre for Road Safety and the Amy Gillet Foundation.

The foundation was established in 2005 after the death of the elite Australian cyclist, who was killed while training in Germany.

"Cyclists are extremely vulnerable on the roads and it's tragic that there has been so many cyclist lives lost in less than six months," Marg Prendergast, general manager for the Centre for Road Safety, said on Wednesday.

"Most concerning is that the coming winter months are traditionally the worst for cyclist casualties, with fewer daylight hours and more cyclists often taking to the road, having been inspired by the annual Tour de France."